Dependency Management Strategies

When working with a monorepo, one of the key architectural decisions is how to manage dependencies across your projects. This document outlines two main strategies and helps you choose the right approach for your team.

The core decision comes down to:

  1. Independently maintained dependencies in individual projects
  2. A "single version policy", where dependencies are defined once at the root for your entire monorepo

Nx fully supports both strategies - it's your choice and you can change your approach as your needs evolve, you are never locked in. You can even mix these strategies, using a single version policy for most dependencies while allowing specific projects to maintain their own versions when necessary. Thanks to its smart dependency graph analysis, Nx can trace dependencies used by different projects and can therefore avoid unnecessary cache misses even when a root level lockfile changes, so that is not a concern.

Let's examine the trade-offs of each approach, using JavaScript/TypeScript as our primary example (though these principles apply to other languages as well):

Independently Maintained Dependencies

In this model, each project maintains its own dependency definitions. For JavaScript/TypeScript projects, this means each project has its own package.json file specifying runtime dependencies, with development dependencies often still living at the root of the workspace (although they can also be specified at the project level). During builds, each project's bundler includes the necessary dependencies in its final artifact. Dependencies are typically managed using package manager workspaces (npm/yarn/pnpm/bun).

While this approach offers flexibility, it can introduce complexity when sharing code between projects. For example, if project1 and project2 use different versions of React, what happens when they try and share components? This can lead to runtime issues that are difficult to detect during development and challenging to debug in production.

A common pitfall occurs when developers have one version of a dependency in the root node_modules but a different version specified in their project's package.json. This can result in code that works locally but fails in production where the bundled version is used.

Pros:

  • Teams can independently choose and upgrade their dependencies
  • More immediately clear what dependencies are intended for each project
  • Easier transition for teams new to monorepos
  • Modern tooling around e.g. module federation can help mitigate some of the challenges within applications

Cons:

  • Complicates deployment when projects share runtime dependencies
  • Makes code sharing between projects more challenging
  • Can lead to hard-to-detect runtime conflicts
  • Increases maintenance and strategy overhead with multiple versions to track

Single Version Policy

This strategy centralizes all dependency definitions in the root package.json file, ensuring consistent versions across your codebase. While individual projects may still maintain their own package.json files for development purposes, the root configuration serves as the single source of truth for versions.

For building and deployment, you'll need to ensure each project only includes its relevant dependencies. Nx helps manage this through its workspace dependency graph and the @nx/dependency-checks ESLint rule, which can automatically detect and fix dependency mismatches between project and root configurations.

The main challenge with this approach is coordinating dependency updates across independent teams. When multiple teams work on different, or even the same, applications within the same repo, they need to align on dependency upgrades. While this requires more coordination, it often results in less total work - upgrading a dependency once across all projects is typically more efficient than managing multiple separate upgrades over time.

Pros:

  • Ensures consistent dependency versions, preventing runtime conflicts
  • Simplifies code sharing between projects
  • Makes workspace-wide updates more manageable and easier to track

Cons:

  • Requires coordination between teams for dependency updates
  • May slow down teams that need to move at different velocities
  • Needs stronger governance and communication processes

For details on using Nx's dependency graph in your deployment process, see our guide on preparing applications for deployment via CI.